Stitch formation



' Oct. 8, 1946. J. H. PIKUL 2,409,149

STITCH FORMATION Original Filed Feb. 21, 1944 4 SheetS-Sheet 2 (96 y J5 .ya J5 ct. 8, B946. J. H. PIKUL STITCH FORMATION original Filed Feb. 21, .w44v

4 Sheets-Sheet 3 INVEN+CIRI- QLCPM u 0d. 8, 1946, J. H. PIKUL 2,409,149

STITCH lFORMATIQN Original Filed Feb. 2l, 1944 4 Sheets-Sheet 4 l Patented Get. 8, 1946 UNITED STATES PATENTl OFFICE STITCH FORMATION Joseph H. Pikul, West Newton, Mass., assigner to i.

The Reece Corporation, a corporation of Maine Original application February 21, 1944, Serial No.

4 Claims.

This invention relates to the art of sewing and more particularly to the formation of atying stitch in material. The present application is a division of my copending application, Serial No. 523,173, filed February 21, 1944.

Heretofore, when chain stitches were resorted to in machine sewing, it was necessary to terminate any group of continuous chain stitches with a conventional tying stitch in order to secure the entire group of stitches against unravelling. An example of a sewing machine of tins type is shown and described in my prior Patent No. 2,131,387, dated September 27, 1938. While a conventional tying stitch secures a group of chain stitches in an entirely satisfactory manner, its formation by the same instrumentalities which form the chain stitches involves at least a different operation of these instrumentalities, which complicates the machine and accordingly increases the cost of the same.

It is the primary aim and object of the present invention to secure a machine-sewed group of continuous chain stitches against unravelling by devising a terminating tying stitch the formation of which is readily accomplished by the same instrumentalities that form the chain stitches without, however, requiring a dierent operation of said instrumentalities.

The invention will be more clearly understood from the following description in conjunction with the accompanying drawings, in which:

Fig. 1 is a greatly magnified bottom View of a piece of material in which successive chain stitches are formed.

Fig. 2 is a section taken substantially on the line 2-2 of Fig. l, and illustrates the conventional concatenation of the loops of a chain stitch.

Fig. 3 is a section taken substantially on the line 3-3 of Fig. l, and shows an intermediate step in the formation of the terminating stitch of a group of chain stitches in accordance with the present invention.

Fig. 4 is a section similar to Fig. 3, showing the last stitch completed.

Figs. 5 and 6 are sections taken substantially on the lines SM5 and 6 6, respectively, of Figs. 3 and 4, respectively.

Fig. 7 is a greatly enlarged, fragmentary sectional view of stitch-forming mechanism for forming a terminating tying stitch in accordance with the present invention.

Figs. 8 and 9 are fragmentary sectional views similar to Fig. 7, showing progressive steps in the formation of the terminating tying stitch.

Figs. 10 and 11 are fragmentary sections taken substantially on the lines lll-l and II-l l, respectively, of Figs. 7 and 9, respectively.

Fig. l2 shows a modified element of the stitchforming mechanism whereby a modified tying stitchis obtained. Fig. 13 is a greatly magnified section through the partly completed, modiiied tying stitch, the

section being similar to the section of Fig. 5.

Fig. 14 is a section similar to Fig. 13, showingv the modified stitch completed. ,f

Fig. 15 is a greatly magnified illustration of th tying stitch of the present invention at the end of a straight seam of chain stitches.

Fig. 16 is a greatly enlarged, fragmentary sectional view of a modied stitch-forming mecha- IllSm.

Fig. 17 is a fragmentary sectional View simila to Fig. 16, showing the formation of another modied tying stitch in accordance With the present invention.

Fig. 18 is a fragmentary section taken substantially on the line l8-l8 of Fig. 17.

Fig. 19 is a front elevation, partly broken away, of a machine embodying the stitch-formingl mechanism shown in Figs. 7 to 9. f

Referring to the drawings, Fig. 1 illustrates greatly magnified the back side of a piece of ma.

terial Win which successive chain stitches 30 are formed. By way of example, these stitches vare shown as arranged in zig-zag fashion. The formation of the chain stitches is conventional, the machine which may be used for this purpose providing a reciprocatory and laterally Vibratory needle 3l (Fig. 19) and two loopers 32 which alternately cooperate with the needle 3| in the:

formation of successive chain stitches. Fig. 7 illustrates a step in the normal cooperation-of tion shown in Fig. 7 with the last loop Z held onvsaid loopen While the last loop l is thus held on the looper 32', a blade or deflector 33 below lthe throat plate 3d is linearly moved from the position shown in Figs. 7 and 10 into the position` shown in Figs. 9 and 11 to deflect the divergng legs of said loop Z. The deflector 33 is provided with a slot 35 (Fig. l0) of a width substantiallyequal to the thickness of Ythe needle thread t. and a wedge-shaped notch 35 which leads intothe slot 35. Hence, on movement of the deflector 33 from the position shown in Fig. 7 into that shown in Fig. 9, the two legs of the loop Z are guidedtoward the slot 35 by the notch 36 and enter said slot onebehind the other. In theD the needle 3l and one of the loopers 32 inthe. formation of the chain stitches, the looper 32` present instance, the deiicctor 33 is so coordinated with the looper 32' that the slot 35 in said deector is in line with the rear leg Zx of the loop Z so that, on movement of said deflector from the position shown in Figs. 7 and 10 into that shown in Figs. 9 and 11, said leg ZX enters said slot 35 without engaging a wall of the V-shaped notch 36, while the front leg ZY of the loop Z is cammed into the slot 35 by the wall 33' of the Vlshaped notch 3E. Consequently, the rear leg ZX-of the loop Z Will enter the slot 35 before the `front leg ZV is cammed thereinto, with the result that the portions of these legs which extend from the deflector 33 substantially to the material W become superpOSed with the front leg Zy nearest the material W (Figs. 8 and 9). Since the loop Z is being distended while being deflected, and since the conventional needle thread tension devices of the machine resist with considerable force the drawing of needle thread through the needle while the loop Z is being deflected as described, the distending loop l will draw thread from the preceding loop Z (Figs. 7 and 8) until the latter is drawn tight. The rear wall 38 of the slot 35 in the deilector 3 3 is rounded asshown in Figs. 7 to 9 so as to avoid chang the thread of the distending loop Z. In order to permit the contracting loop Z to close as tightly as possible about the legs of the loop Z when the latter is being distended (Figs. and 9) the delector 33 brings the legs of the loop Z preferably 'as closely as possible to the convergence C of the legs of the preceding loop Z' (Figs. 9 and 1l). To this end, the deiiector 33 is arranged to deflect the legs of the loop l as closely as possible to the material W (Fig. 9), the deflected legs of the loop being received in a cut-away portion 39 of the throat plate 34. To the same end. the deector 33 is moved in such a direction that the legs of the loop Z between the deflector and the material (Fig. l1) pass the convergence C of the legs of the loop Z' as closely as possible so that said loop Z may contract into firm wedging engagement with the legs of the loop Z without undue restraint from the latter. The contracting loop Z', through intermediation of the legs ZX and Zy of the loop Z` also draws the loop Z, which immediately precedes the loop Z', firmly against the material W (Figs. 3 and 9). Shortly'before the deflector 33 reaches the most advanced position shown in Fig. 9, the same brings the rear leg ZX of the loop Z into engagement with a knife El on the looper 32 (Figs. 9 and 11), whereupon said leg is severed as at di. On subsequent removal of the material W from the machine, the severed portion of the loop 7 which is continuous with the needle thread is withdrawn from the material, leaving the severed rear leg ZK of said loop Z anchored between the loops Z and Z (Figs. 4 and 6). The pull exerted by the distending loop Z on the thread. of the preceding loop Z is so great that the thread of said loop Z as well as of the loop Z is stretched within the limit of its resiliency, and the contracted loop Z' draws the loop Z against the loop Z with such force that the engaged portions of said loops are considerably deformed and constricted (Figs. 3 and 5). The thread of the contracted loop Z is in fact stretched to such an extent that the withdrawal therefrom of the severed end of the'loop Z does not cause any noticeable relaxation of its firm grip on the remaining portion of the severed loop Z, the loop Z having sufficient resiliency to contract and hold the adjacent -portion of the remainder o f the severed loop Z deformed and-constricted as shown'in Figs. land 6.

' under the microscope, the crossover leg Zz of the That the loop Z' is under permanent tension and does not noticeably relax its firm grip on the severed loop Z, even after the withdrawal of the severedv end thereof, is evidenced by a very marked cross-sectional constriction of the leg Zx between the loop l and the material W (Fig. 4) as observed under a microscope. As also observed last stitch is partly embedded in the material W (Fig. 4) in consequence of the permanent tension in the thread of said last stitch. The tied chain stitch shown in Figs. 4 and 6 has dei-led al1 ordinary efforts to unravel or even loosen the same, wherefore said stitch serves as, and is in fact, a novel tying stitch which is as well secured against unravelling as a conventional tying Stitch.

Whereas the ,described deflector 33 has a provision (narrow slot 35) for forcing the deflected legs of the loop Z into superposed relatipn along the material W (Fig. 9), a modified deflector Al5 (Fig. 12) merely forces the diverging legs of the loop Ztogether. To this end, the defiector 45 has a wedgefshaped notch ,45 the bottom l? of which is rounded. 0n movement of the deflector /l5 in the direction of the arrow 48 in Fig. 12, the diverging legs of the loop Z on the looper 32' will, besides being de ilected, also be forced into sideby-side engagement with one another by the rounded bottom lll of the ,notch 46, resulting in the disposition of the legs of the loop Z in the contracted loop Z as shown in Fig. 13. After severance of the loop Z and withdrawal of the severed end thereof from the contracted loop Z', the remaining end the severed loop is wedged against the contracted loop Z (Fig. 14) and against the preceding loop Z" in much the same fashion assbowo in Figs. 4 and 6- Fig. l5 .shows the novel tying stitch applied at the end of a straight seam of chain stitches 50, the contracted loop 5I of the last stitch firmly wedging the vremaining end 52 of the last severed loop against the loop 53 which immediately precedes the loop 5i. In View of the preceding, detailed description of the formation of the n ovel tying stitch at the end of a Zig-zag seam of chain stitches, the formation of the same tying stitch at the end of a straight seam of chain stitches is too obvious to require furtherexplanation.

Figs. 1 6 and 17 disclose a modified mode of tyingthe last one of a series of chain stitches. The machine used Vfor forming these stitches may be like the one used for forming the stitches 3D in Fig. 1, and comprise a reciprocatory and vibratory needle (not shown) carrying needle thread t, and a pair of alternately operative loopers of which one is shown at 55. After the sewing instrumentalities of the machine come to rest with the needle retracted land the looper 55 in the position shown in Fig. 1'6 and holding the last loop 56, a deflector 5l underneath the throat plate 58` is movedin the Ydirection of the arrow 59 in Fig. 18 to deflect the front leg 55' in the manner best shown in Fig. 17, thereby distending the loop 56. -The deflected leg 56' of the -distending` Yloop 56 forcesfthe preceding loop 60 againstthe material W and the convergence of the legs of the loop 55. The distending loop, being `unable to draw needle thread through the needle thread tension devices (not shown) of thel machine, must draw thready from the. preceding loops 60 and 6|. Sincethe loop 6.0 is prevented from contracting by the deflected leg -56 of the last loop 55 (Fig. 17), the latter `will -drawdthread from the loop El whichlmmediately.precedesthe loop 53. The ensuing contraction of the loop 6l draws the loop 33 into firm wedging engagement with the material W and the convergence of the legs of the loop 53 and at the same time forces said loop El toward the convergence of the legs of the last loop 53 (Fig. 17), so that, after severance of the last loop 53 and withdrawal of the severed end of said loop from the material, the end of the severed loop remaining in the material is held fairly securely between the loops 60 and 6I. The deflector l has preferably an inclined cutting edge 62 (Fig. 18) which engages and severs the rear leg 55" of the loop 56 as at 33 when the front leg 53 thereof is deflected as shown in Figs. 17 and 18. A last stitch tied in this fashion, while not as rmly secured as the previously described stitch shown in Fig. 4, for instance, is nevertheless satisfactory for many purposes.

Fig. 19 shows an example of a machine which may be equipped with mechanism to form the novel tying stitch shown in Figs. 4 and 6, for instance. This machine is a button hole sewing machine of the type known as straight hole machine, described, for example, in U. S. Patents Nos. 714,284, November 25, 1902; 749,776, January 19, 1904; 1,088,652, February 24, 1914; 1,402,073', January 3, 1922, and 1,483,307, February 12, 1924. The machine comprises a bed 65 from which rises a standard 66, carrying an overhanging arm 3l spaced above the bed. The material or work W is carried by a work clamp or holder comprising a clamp plate 68 and cooperating clamping arms (not shown), said work holder being movable as a unit over the bed, by mechanism not shown, in order to position the stitches along the sides of the buttonhole. The stitch-forming instrumentalities comprise the previously mentioned, eye-pointed needle 3l above the work and cooperating loopers or equivalent under thread handling devices 32 below the work, the throat plate 34 being carried by the bed 55 and having an opening 10 through which the needle operates. The needle 3l is carried by a needle bar H which is longitudinally and vertically reciprocated, by means generally indicated at 12, in a needle bar guide 13, means (not shown) being provided for oscillating said needle bar alternately in opposite directions transversely to the direction of feed of the work clamp between successive strokes of the needle to position the depth stitches. The thread t from a suitable source passes, through a take-up 'i4 and suitable tension devices (one being shown at 16) to the needle eye, whence it passes through the work and throat plate to the loopers 32. The present machine is power-operated and automatically stopped at the end of an operating cycle by stop-motion mechanism not shown herein but fully disclosed in my referred copending application Serial No. 523,173, filed February 21, 1944.

In accordance with the present invention, a loop deiiector such as the deector 33 in Figs. 9 and 10, for instance, is guided in ways in the bed 35 immediately below the throat plate 34 and between the latter and the loopers 32 (Fig. 19). At the completion of an operating cycle of the machine, and substantially coincidentally with the stopping of the machine, said deflector 33 is moved, by means to be described, from its normal retracted position shown in Fig. 19 to the left as viewed in said figure, to deilect, andlthereby dis- 6 tend, the last loop Zwhich, at this time is held by one of the loopers 32 and extends from the work W about said looper to the needle 3 Iv as shown in Fig. 9. The deflection and simultaneous distention of the loop Z by the delector 33 results in the setting of the last stitch in the manner previously described and shown in Figs. 3 and 5. The looper which holds the last loop Z also preferably carries a knife or cutter 40 which may be like the cutter 49 on the looper 32 in Fig. 9 and severs the rear leg of the loop l toward the end of its distention byr the deilector 33. On subsequent removal of the material W from the machine and according withdrawal of the severed end of the loop l from the material, the last stitch is completed, and this stitch is the same as, and has all the described characteristics of, the novel tying stitch shown in Figs. 4 and 6.

The deflector 33 is provided with a socket III (Fig. 19) to receive a rounded end H2 of an arm H3 which is fast on one end of a rock shaft H4, journalled in suitable bearings in the bed 65. The rock shaft l IA is, at the completion of an operating cycle of the machine, rocked counterclockwise as viewed in Fig. 19, by means fully disclosed in my referred copending application Serial No. 523,173, so that the deiiector 33 will deflect, and thereby distend, the last formed loop l (Fig. 9) in the manner previously described.

I claim:

1. A tying stitch for chain sewing in which the last-formed loop of the thread extends through the work and between the legs of the next to the last-formed loop, and, after emerging from the work, the free end of the thread passes rst over one leg of the next to the last, loop and then through the last loop, said last. loop being drawn tight and pulling the free end against the next to the last loop and the work.

2. The method of forming a tying stitch at the end of a series of chain stitches which comprises extending the last loop and deiiecting it in the general direction of the legs of the preceding loop and thereby tightening the preceding loop until the legs of the loop passing through the last loop are pinched against the last loop and the work and then severing one of the legs of said loop leaving a free end which passes through the last loop and is pinched against the last loop and the work.

3. The method of forming a tying stitch at the end of a series of chain stitches which comprises extending the last loop and deflecting it in the general direction of the legs of the preceding loop thereby tightening the preceding loop, and severing one leg of the last loop after the tightening has pinched the free end against the last loop and the work.

4. The method of forming a tying stitch at the end of a series of chain stitches in work in which the alternate needle holes are arranged in parallel rows which comprises extending the last loop and deflecting it in the general direction of the legs of the preceding loop and thereby tightening the preceding loop, until the legs of the loop passing through the last loop are pinched against the last loop and the work, and then severing one of the legs of said loop leaving a free end which passes through the last loop and is pinched against the last loop and the work.

JOSEPH H. PIKUL. 

